Liquid crystal display device

ABSTRACT

A liquid crystal display device includes first and second substrates, a plurality of gate bus lines and data bus lines on the first substrate, the gate bus lines being perpendicular to the data bus lines, a plurality of pixels defined by the gate bus lines and the data bus lines, the pixels having a plularity of regions, at least a pair of electrodes in each region having a common direction, and a plurality of liquid crystal molecules between the substrates.

[0001] This application claims the benefit of Korean application No.1996-23115 filed on Jun. 22, 1996, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display device,and more particularly, to an in-plane switching mode liquid crystaldisplay device (LCD). Although the present invention is suitable for awide scope of applications, it is particularly suitable for improvingthe quality of picture image.

[0004] 2. Discussion of the Related Art

[0005] As a thin film transistor liquid crystal display device (TFT-LCD)has been widely used for portable televisions or notebook computers, anLCD having a large panel is in great demand. A conventional TFT-LCD,however, has a problem that a contrast ratio is changed with a directionof viewing-angle. Liquid crystal display devices such as a twistednematic LCD having an optical compensator and a multi-domain LCD havebeen proposed to cope with this problem. Nevertheless, such LCDs are notcapable of solving the problem in a variation of the contrast ratio andcolor shifting.

[0006] An in-plane switching mode LCD to realize a wide viewing anglehas also been proposed in the JAPAN DISPLAY 92 Page 457, Japanese PatentUnexamined Publication No. 7-36058, Japanese Patent UnexaminedPublication No. 7-225538, and ASIA DISPLAY 95 Page 707.

[0007] A conventional in-plane switching mode LCD will now be explainedwith reference to FIGS. 1 to 3.

[0008] Referring first to FIGS. 1 and 2, operation of the conventionalLCD will be described as follows. Liquid crystal molecules 8 in a liquidcrystal layer 12 are aligned to have a rubbing direction (θ_(R)) of90°<θ_(R)<180° with respect to a longitudinal elongation direction (0°)of a gate bus line on a substrate as shown in FIG. 2. A polarizationaxis direction (θ_(PL2)) of a analyzer 10 attached on a second substrate5 is parallel to the rubbing direction (θ_(R)). A polarization axisdirection (θ_(PL1)) of a polarizer 9 attached on the first substrate 1is perpendicular to a polarization axis direction (θ_(PL2)) andelectrode elongation directions (θ_(EL)) of a data electrode 2 and acommon electrode 3 are θ_(EL)=90° with respect to the longitudinalelongation direction of the gate bus line. Thus, when a voltage is notapplied to a data electrode 2 and a common electrode 3 as shown in FIG.1A, the liquid crystal molecules 8 are aligned with a slightly tilteddirection relative to the elongation direction (θ_(EL)) of the data andcommon electrodes along with the rubbing direction (θ_(R)) in thesubstrate. The elongation direction (θ_(EL)) of the electrodes isperpendicular to the longitudinal direction of the gate bus line.Conversely, when a voltage having a horizontal electric field parallelto the longitudinal direction of the gate bus line is applied to theliquid crystal layer 12 as shown in FIG. 1B, the liquid crystalmolecules 8 near the first substrate are rotated and a transmittance ofthe liquid crystal layer 12 is changed by a birefringence. A retardationvalue (Δnd) of the liquid crystal layer 12 is about λ/2(for example, Δndwould be approximately 0.21-0.36 μm, where λ is a wavelength of anincident light). For example, when the liquid crystal rotation angle isabout 45 degree, the transmittance is maximum so that a screen of theLCD becomes a black mode.

[0009]FIG. 3A is a plane view of the conventional in-plane switchingmode liquid crystal display device and FIG. 3B is a cross-sectional viewtaken along the line A-A′ in FIG. 3A. The liquid crystal display deviceis protected by a metal frame 22 excluding a representing unit 21 of aliquid crystal panel 32. A gate driving circuit 23, a data drivingcircuit 24, and a back light housing 25 including a back light 31 aremounted on the metal frame 22. In the representing unit 21, an exposureplate 75 (shown in FIG. 3B) having a light diffusion plate, polarizer63, first and second substrates 27 and 26 constituting the liquidcrystal panel 32, and an analyzer 64 are disposed on the secondsubstrate 26. Further, a light compensator (not shown) may be disposedbetween the polarizer 63 and the first substrate 27 or between thesecond substrate 26 and the analyzer 64 to improve the contrast ratio.

[0010] Generally, in the conventional TFT-LCD, the TFT is formed in thefirst substrate 27 as a switching device and the color filter is formedon the second substrate 26. However, a diode may be used as a switchingdevice in a diode LCD and a simple matrix LCD. Alternatively, when theTFT is formed on the second substrate, the color filter is formed ontothe first substrate. Further, a mono-chromiumatic LCD may also be usedwithout the color filter.

[0011] However, the conventional in-plane switching mode liquid crystaldisplay device has a problem of the color shifting with the change ofviewing angle direction. As shown in FIGS. 1C to 1D, when a horizontalelectric field is applied to the electrodes 2, 3, the liquid crystalmolecules 8 nearby the first substrate 1 are aligned parallel to thelongitudinal direction of the gate bus line, whereas the liquid crystalmolecules 8 nearby the second substrate 5 are aligned with an angle of90°-180° relative to the longitudinal direction of the gate bus line.The liquid crystal molecules 8 are thus twisted. Therefore, colorshifting is caused in either blue or yellow in a X or Y viewing angledirection, respectively. This color shifting mainly deteriorates thequality of the picture image.

SUMMARY OF THE INVENTION

[0012] Accordingly, the present invention is directed to a liquidcrystal display device that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

[0013] An object of the present invention is to provide an in-planeswitching mode liquid crystal display device having an improved pictureimage quality by preventing color shifting.

[0014] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0015] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly described, aliquid crystal display device includes a substrate, a gate bus line anda data bus line elongating horizontally and vertically to form a matrixfigure, a pixel which is divided into several regions defined by thegate bus line and the data bus line, a data electrode and a commonelectrode in each region of the pixel, and alignment layer over thesubstrate.

[0016] In another aspect of the present invention, a liquid crystaldisplay device includes first and second substrates, a plurality of gatebus lines and data bus lines on the first substrate, the gate bus linesbeing perpendicular to the data bus lines, a plurality of pixels definedby the gate bus lines and the data bus lines, the pixels having aplurality of regions, at least a pair of electrodes in each regionhaving a common direction, and a plurality of liquid crystal moleculesbetween the substrates.

[0017] In another aspect of the present invention, a liquid crystaldisplay device includes first and second substrates, a plurality of gatebus lines and data bus lines on the first substrate in a matrix form, aplurality of pixels defined by the gate bus lines and the data buslines, the pixels having first and second regions, at least one commonbus line at each pixel, the common bus line being parallel to the gatebus line, at least a pair of first and second electrodes in the firstand second regions, respectively, the first and second electrodes havingfirst and second electrode elongation directions (θ_(EL1) and θ_(EL2))with respect to a longitudinal direction of the common bus line, a colorfilter layer over the second substrate, first and second alignmentlayers over the first and second substrates, the first and secondalignment layers having first and second alignment directions (θ_(R1)and θ_(R2)), respectively, a liquid crystal layer between the firstsubstrate and the second substrate, a polarizer and a analyzer attachedto the first substrate and the second substrate, respectively.

[0018] In another aspect of the present invention, A liquid crystaldisplay device having a plurality of pixels each including a pluralityof regions, the device includes first and second substrates, a liquidcrystal molecular layer having liquid crystal molecules between thefirst and second substrates, a plurality of electrodes in each region ofthe pixels, an electric field parallel to the substrates applying to theelectrodes, and first and second alignment layers over the first andsecond substrates, respectively, the first and second alignment layershaving first and second alignment directions of θ1 and θ2 relative to anelectrode elongating direction.

[0019] In a further aspect of the present invention, a liquid crystaldisplay device having a plurality of pixels each including a pluralityof regions, the device includes first and second substrates, a liquidcrystal molecular layer having liquid crystal molecules between thefirst and second substrates, a plurality of electrodes on the firstsubstrate in each region of the pixels, an electric field parallel tothe substrates applying to the electrodes, a different electric fieldfrom that of a neighboring region to rotate the liquid crystal moleculesin opposite directions in each neighboring region applying to theelectrodes in each region, and first and second alignment layers overthe first and second substrates, the first and second alignment layersproviding for first and second alignment directions of θ₁ and θ₂.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention. In the drawings:

[0021]FIGS. 1A to 1D are schematic views illustrating an operation of aconventional in-plane switching mode liquid crystal display device.

[0022]FIG. 2 illustrates an axis directional relationship in theconventional in-plane switching mode liquid crystal display device.

[0023]FIG. 3A illustrates the conventional in-plane switching modeliquid crystal display device.

[0024]FIG. 3B is a cross-sectional view of the conventional in-planeswitching mode liquid crystal display device taken along the line A-A′in FIG. 3A.

[0025]FIG. 4 is a plane view of a liquid crystal display device inaccordance with a first embodiment of the present invention.

[0026]FIG. 5 is a cross-sectional view taken along the line B-B′ of FIG.4.

[0027]FIG. 6 illustrates an axis directional relationship of thein-plane switching mode liquid crystal display device in accordance withthe first embodiment of the present invention.

[0028]FIGS. 7A to 7D are schematic views illustrating an operation ofthe in-plane switching mode liquid crystal display device in accordancewith the first embodiment of the present invention.

[0029]FIG. 8A illustrates a gray invention region in the conventionalin-plane switching mode liquid crystal display device.

[0030]FIG. 8B illustrates a gray inversion region of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment of the present invention.

[0031]FIG. 9 illustrates a driving voltage waveform of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment of the present invention.

[0032]FIG. 10 is a plane view of the in-plane switching mode liquidcrystal display device in accordance with a second embodiment of thepresent invention.

[0033]FIG. 11 is an axis directional relationship of the in-planeswitching mode liquid crystal display device in accordance with thesecond embodiment of the present invention.

[0034]FIG. 12 is a plane view of the in-plane switching mode liquidcrystal display device in accordance with a third embodiment of thepresent invention.

[0035]FIG. 13 is an axis directional relationship of the in-planeswitching mode liquid crystal display device in accordance with thethird embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings.

[0037] Hereinafter, an in-plane switching mode liquid crystal displaydevice according to a first embodiment of the present invention will bedescribed with reference to FIGS. 4 to 9.

[0038] Referring to FIGS. 4 and 5, a liquid crystal panel includes a TFT55, a color filter layer 61, alignment layers 59, 62 over the first andsecond substrates 27, 26, respectively, a liquid crystal layer 60, and aspacer 65 between the first and second substrates 27, 26 to maintain aconstant distance between the substrates 27, 26 and a polarizer on bothsurfaces of the liquid crystal panel.

[0039] In FIG. 4, the TFT 55 on the first substrate 27 is disposed at aregion where a gate bus line 41 and data bus line 42 are crossedperpendicularly with each other. A common bus line 43 parallel to thegate bus line 41 is formed in the center of a pixel in a matrix form. Acommon electrode 49 connected to the common bus line 43 is formed in thepixel. A data electrode 48 connected to the drain electrode 47 of theTFT 55 is formed in parallel to the common electrode 49.

[0040] Referring to FIGS. 5 and 6, the pixel is divided into a firstregion I and a second region II the by common bus line 43. θ_(EL1) is anelectrode elongation direction in the first region I, and θ^(PL1) is apolarization direction of polarizer 63. θ_(EL2) is an electrodeelongation direction in the second region II, and θ_(PL2) is apolarization direction of analyzer 64. θ_(R) is a rubbing direction,θ_(LC1) and θ_(LC2) are optical axis directions of a liquid crystalmolecules in the first and second region, respectively. Electrodeelongation directions of the first region I and the second region II aresymmetric to the common bus line 43. Thus, the angles θ_(EL1), θ_(EL2)of the electrodes in each region I, II relative to the common bus line43 are the same. A voltage is applied to the gate bus line 41 in thelongitudinal direction of the liquid crystal display device. The rubbingdirection of the first substrate 27 is not parallel to that of thesecond substrate 26. The rubbing direction is parallel to thepolarization direction (θ_(PL2)) of the analyzer 64. The polarizationdirection (θ_(PL2)) of the analyzer 64 is perpendicular to thepolarization direction (θ_(PL1)) of the polarizer 63.

[0041] The gate bus line 41, the common bus line 43, and the commonelectrode 49 are made of an AlTa thin film (3% Ta content) having athickness of 0.3 μm deposited by a sputtering process. The AlTa thinfilm surface is anodized to form the AlTa oxidation layer 52 having athickness of 0.1 μm, so that the electrode surface has a higherinsulation characteristic. Also, a short circuit due to a thin thicknessis prevented on the electrode surface. After a gate insulating layer 57having a thickness of 0.3 μm, an amorphous silicon (a-si) layer 44having a thickness of 0.2 μm, and n⁺-Si layer are consecutivelydeposited on the AlTa oxidation layer 52 by PECVD (plasma enhancedchemical vapor deposition), a photoetching process is executed to formthe TFT 55.

[0042] Then, a chromium layer having a thickness of 0.1 μm is depositedon the TFT 55 and etched by the sputtering process. A photoetchingprocess is further conducted to form a source electrode 46, drainelectrode 47 of the TFT 55, and the data electrode 48. The n⁺-siliconlayer on a channel unit of the TFT 55 is removed by a dry-etchingprocess using the source electrode 46 and the drain electrode 47 asmasks. Thus, a-Si layer remains only on the channel unit. Thereafter, apassivation layer 58 having a thickness of 0.2 μm is deposited on theentire surface over the first substrate 27 by PECVD. For example,Si_(X)N_(Y) may be used as the passivation layer 58. Subsequently, thepassivation layer 58 is partially etched on the end portion of the gatebus line 41 and data bus line 42 to connect the bus lines 41, 42 withthe outer driver circuit.

[0043] A storage capacitor 53 (shown in FIG. 4) is formed at anoverlapping region of the common bus line 43 and a data electrode 48.The storage capacitor 53 maintains uniform the electric charges of thedata voltage in the each pixel.

[0044] A black matrix 51 (shown in FIG. 5) and a color filter layer 61are formed on the second substrate 26. An overcoat layer (not shown) isformed on the black matrix 51 and the color filter layer 61 to obtainthe high stability of the surface and improve the flatness. The blackmatrix 51 prevents the leakage of light at the gate bus line 41, thedata bus line 42, the common bus line 43, and the TFT 55. The blackmatrix 51 is formed by etching a Cr/Cr_(x)O_(Y) layer having a thicknessof about 0.1 μm in each region. R, G, and B layers are formedrespectively on the color filter layer of the each pixel.

[0045] In the aforementioned-structure of the LCD, the widths of dataelectrode 48, the common electrode 49 and the gap between the electrodesare 5 μm each.

[0046] An alignment layers 59, 62 are formed on the first and secondsubstrates 27 and 20 by depositing and baking a serial No.RN1024 ofNissan Chemical having a thickness of 0.08 μm. While the alignment layer59 over the first substrate 27 is rubbed in the direction of −90° withrespect to elongation direction of the common bus line, the alignmentlayer 62 on the second substrate is rubbed in the direction of 90°. Fora spacer 65, a Micropearl of SEKISUI FINE CHEMICAL having a diameter of6.4 μm is used to have a liquid crystal layer 60 having a thickness of6.2 μm. And for liquid crystals, a positive liquid crystal such as ZGS5025(Δn=0.067, Δε=6.0) of CHISSO C0. is used. At this time, the pre-tiltangle of the aligned liquid crystal molecules is about 4.8°, and theretardation value (Δnd) is about=0.41.

[0047] The optical transmission axis direction (θ_(PL1)) of thepolarizer 63 attached to the first substrate 27 is parallel to thelongitudinal direction of the gate bus line 41. The optical transmissionaxis direction (θ_(PL2)) of the analyzer 64 attached to the secondsubstrate 26 is perpendicular to the longitudinal direction of the gatebus line 41.

[0048] The gap between the data electrode 48 and the common electrode 49is thinner than a thickness of liquid crystal layer and the retardationvalue (Δnd) of the liquid crystal satisfies the following equation.

λ/2<(Δnd≦λ

[0049] where, Δn is an anisotropy of a refractive index of the liquidcrystal, d is a thickness of the liquid crystal layer, and λ is awavelength.

[0050] The data electrode 48 and the common electrode 49 in the firstregion I and the second region II are formed to have angles θ_(EL1) andθ_(EL2), respectively, with respect to the common bus line 43. The dataelectrode 48 and the common electrode 49 are symmetric with each other.

[0051] Operation of the present in-plane switching mode liquid crystaldisplay device will now be described with reference to FIGS. 7A to 7D.FIGS. 7A and 7B are cross-sectional views of the in-plane switching modeliquid crystal display device and a plane view of off-state LCD, andFIGS. 7C and 7D are for on-state LCD, respectively.

[0052] The elongated direction of the conventional electrodes has anangle of 90° relative to the longitudinal direction (0°) of the gate busline. However, the electrodes of the present invention on the firstregion I and the second region II are respectively extended in thedirections with angles θ_(EL1) and θ_(EL2) relative to the longitudinaldirection of the gate electrode. The electrodes in the first region Iand in the second region II are thus symmetric with each other. Here,the value of the angles satisfies the following equations.

0°<θ_(EL1)<90°, −90°<θ_(EL2)<0°, and |θ_(EL1)|=|θ_(EL2)|.

[0053] When the voltage is not applied to the electrodes, the opticalaxis of all the liquid crystal molecules in the liquid crystal layer,set in between the first substrate 27 and the second substrate 26 isaligned almost parallel to the substrate by the alignment layer 59, 62,as shown FIGS. 7A and 7B. For example, the liquid crystals between thesubstrates are nematic liquid crystals without a choral dopant. A light11 incident to the first substrate 27 is polarized linearly by thepolarizer 63, transmitted to the liquid crystal layer 60, and reachesthe analyzer 64. However, since the polarization directions of theanalyzer 64 and the polarizer 63 are perpendicular with each other, thelight 11 is not transmitted to the analyzer 64. Therefore, the LCDscreen becomes a black mode.

[0054] Conversely, when the voltage is applied to the electrodes 48, 49,a parallel electric field 13 is applied in the liquid crystal layer 60through a data voltage between the data electrode 48 and the commonelectrode 49. The parallel electric field 13 has a maximum value (E₁) onthe surface of an alignment layer 59 of first substrate 27, a nearthreshold value (E₂) on the surface of the alignment layer 62 of thesecond substrate 26, and a medium value (E_(M)=(E₁+E₂)/2) in the middleof the liquid crystal layer. When the parallel electric field 13 is notuniform, the intensity of the parallel electric field 13 becomesgradually smaller from the first substrate 27 to the second substrate26. Such a non-uniform electric field in the liquid crystal layer 60 canbe formed by making the thickness of the liquid crystal layer 60 largerthan the gap between the electrodes. A liquid crystal molecule 77 a,which is near the surface of alignment layer 59 in the first region I,is affected by the non-uniform electric field. The optical axisdirection (θ_(LC1)) of the liquid crystal molecules is thus changed tobe perpendicular to the electrode elongation direction (θ_(EL1)).

[0055] Similarly, in a liquid crystal molecule 77 b near the surface ofalignment layer 59 in the second region II, the optical axis direction(θ_(LC2)) is also changed to be perpendicular to the electrodeelongation direction (θ_(EL2)) in the second region II. Further, sincethe electric field applied to the liquid crystal molecules 78 a, 78 bnear the surface of the alignment layer 62 in the regions I, II is thenear threshold value, the molecules 78 a, 78 b are not affected by theelectric field so that the optical axis is not changed. Therefore, byapplying the non-uniform electric field, the liquid crystal molecules inthe liquid crystal layer between the substrates 26, 27 are graduallychanged from the first substrate 27 to the second substrate 26. As aresult, the molecules are in a twisted state.

[0056] The liquid crystal molecules 77 a, 78 a are twistedcounterclockwise from a direction parallel to the rubbing direction(θ_(R)). The direction is perpendicular to the longitudinal direction ofthe gate bus line 41 and the direction of θ_(LC1) in the first region I.The liquid crystal molecules 77 b, 78 b are twisted clockwise from adirection perpendicular to the longitudinal direction of the gate busline 41 and the θ_(LC2) in the second region II. As a result, the liquidcrystal molecules in the first region I and the second region II aretwisted in the opposite direction with each other.

[0057] When the linearly polarized light 11 through the polarizer 63 istransmitted to the liquid crystal layer 60, the polarization directionof the light is rotated by the twisted liquid crystal layer 60 and theoptical axis direction is directed to the same direction of thepolarization direction in the analyzer 64. The light 11 linearlypolarized by the polarizer 63 and transmitted to the liquid crystallayer 60 is thus transmitted to the analyzer so that the LCD screenbecomes a white mode.

[0058] Here, the amount of the light transmittance depends on thetwisted angle of the liquid crystal molecules. Thus, when the twistedangle of the liquid crystal molecules become larger, the amount of lighttransmittance also becomes larger. A grey level of the liquid crystaldisplay device can also be controlled with the data voltage by twistingthe liquid crystal molecules.

[0059] For example, when the voltage applied to the electrode is 1V-5V,the liquid crystal molecules in the first region I and the second regionII are arranged symmetrically with each other by the electric field ofthe each region having an intermediate grey level. Thus, the colorshifting occurred in the viewing angle directions of X, Y the firstregion I and the second region II is different from each other. Theviewing angle direction of X causes the blue shift and the viewing angledirection of Y causes the yellow shift in the first region I. On theother hand, the viewing angle direction of X causes the yellow shift andthe viewing angle direction of Y causes the blue shift in the secondregion II. Therefore, the total color shifting caused by thebirefringence ratio of the liquid crystal molecules is corrected by thecolor shifting in the first and second regions I, II, so that thedesired color can be obtained in whole pixels.

[0060] In order to maximize the optical transmittance ratio of theliquid crystal layer 60 at the maximum voltage, the retardation value(Δnd) of the liquid crystal layer 60 must be about 0.74λ. Accordingly,the anisotropy of the refractive index (Δn) and a thickness of theliquid crystal layer (d) has to be limited to get the maximum opticaltransmittance ratio. The general twist nematic liquid crystal layer hasthe anisotropy of refractive index of about 0.06-0.09 and the thicknessof 6.0-8.8 μm when the wavelength of the incident light is about 0.56μm.

[0061]FIG. 8A and FIG. 8B illustrate the viewing angle characteristicsaccording to the conventional in-plane switching liquid crystal displaydevice and the first embodiment in-plane switching liquid crystaldisplay device, respectively. Hatched regions are viewing angle regionswith the contrast ratio of 10:1 or less. As shown in FIG. 8A, theregions have the lower contrast ratio at four inclined viewing angledirection in the conventional liquid crystal display device.

[0062] In the present liquid crystal display device, the regions alsohave the lower contrast ratio at four inclined viewing angle direction,as shown in FIG. 8B, but the regions are much smaller than the regionsin the conventional LCD. That is, the liquid crystal display device ofthe present invention provides regions having a contrast ratio more than10:1 is larger than the conventional in-plane switching LCD. Also, theviewing angle characteristic is improved in both the vertical andhorizontal directions. This results from the color shifting according tothe viewing angle becomes smaller and the contrast ratio of the screenis increased.

[0063]FIG. 9 is a driving voltage waveform of the liquid crystal displaydevice according to the first embodiment. For example, in thisembodiment, the screen size is 12.1 inch and the pixel number of480*640(*R•G•B). A gate voltage V_(GH), ground voltage V_(GL), andcommon voltage V_(co) are 20, 0, and 8V, respectively, and a pulse widthis 31 μs. The data voltage V_(D) is taken as a single pulse signalhaving a frequency of 31 μs, and a maximum ±6V, and minimum ±1V withrespect to the common voltage V_(CO). The data voltage V_(D) may becontrolled to have 5V in the signal region. Also, by adjusting thecommon voltage, the AC voltage is applied between the common electrode49 and the data electrode 48.

[0064] Materials for the alignment layers on the first substrate and thesecond substrate do not have to be the same in the present invention. Onthe first substrate, for example, the alignment layer including amaterial having a lower anchoring energy and a lower rubbing density maybe coated to rotate the liquid crystal molecules easily. On the otherhand, the alignment layer such as polygamic acids base material having alower pre-tilt angle and good absorption characteristics of impurityfrom the liquid crystal may be coated on the second substrate to improvethe viewing angle characteristics and remove the after-image.

[0065] Also, the pixel is divided into the first region and the secondregion in the first embodiment. Moreover, when the pixel is divided intomore than two regions, the first region and the second region may bearranged to have more effective liquid crystal display devices.

[0066] Referring to FIGS. 10 and 11, a second embodiment in the presentinvention will be described as following. As shown in the FIG. 10, thepixel is divided into a first region I and second region II. A commonbus line 153 is formed between the regions I and II. A common electrode148 in the second region II is connected to a source electrode 147 ofthe TFT. The common electrode 148 in the first region is elongated inthe directions of θ_(EL1)=90° relative to longitudinal direction of thegate bus line 141 (i.e., 0° in FIG. 11) and 90°<θ_(EL2)<180° in thesecond region. A rubbing angle direction (θ_(R)) in the alignment layeris relative to the longitudinal direction of the gate bus line 141. Theangle θ_(R) of the rubbing direction in the alignment layer is largerthan the angle θ_(EL1) of the electrode elongation direction in thefirst region, and smaller than the angle θ_(EL2) of the electrodeelongation direction in the second region. Thus, the relationship amongthe angles of θ_(EL1), θ_(R), θ_(EL2), is, θ_(EL1)<θ_(R)<θ_(EL2).Therefore, the liquid crystal molecules in the first region I and thesecond region II are aligned symmetrically with each other and rotatedin the opposite direction with each other having the intermediate greylevel in the applied voltage state. Therefore, the color shiftingaccording to the viewing angle direction is compensated as similarly inthe first embodiment.

[0067] Referring to FIGS. 12 and 13 a third embodiment will bedescribed. An optical axis direction of the pixel is shown in FIG. 13.While the electrode elongation direction is divided into several regionsin the pixel in the first and second embodiments, the electrodeelongation direction of all of the pixel is the same and a rubbingdirection is different from each region. Further, it is possible tocontrol the alignment state of the liquid crystal molecules in eachregion in the third embodiment. The angles θ_(EL1), θ_(EL2) of electrodeelongation directions on the first region I and the second region II areθ_(EL1)=90°, θ_(EL2)=90°, respectively, relative to the longitudinaldirection (shown as 0° in FIG. 13) of the gate bus line 241, and theangles θ_(R1), θ_(R2) of rubbing directions in each region are0°<θ_(R1)<90°, −90°<θ_(R2)<0°. Also, the relationship between therubbing direction (θ_(R1)) of the first region I and the rubbingdirection (θ_(R2)) of the second region II is θ_(R1)=−θ_(R2). The liquidcrystal molecules on the first region I and the second region II arethus rotated clockwise and counterclockwise, respectively. The moleculesare in the opposite direction with each other at an intermediate greylevel in the applied voltage state and aligned symmetrically relative tothe longitudinal direction of the gate bus line 241. Thus, the colorshifting according to viewing angle direction is compensated in thisembodiment.

[0068] The rubbing process is to determine the alignment direction ofthe alignment layer in the each embodiments. The alignment direction mayalso be determined by irradiating the ultraviolet light into thealignment layer using the light alignment material as an alignmentlayer.

[0069] The present invention provides an in-plan switching mode liquidcrystal display device that the pixel is divided into a plurality ofregions. The data electrode and the common electrode of each region aresymmetric relative to the longitudinal direction of the gate bus line.The electrode elongation direction is in common relative to thelongitudinal direction of the gate bus line and the rubbing directionsare different from each region. The color shifting is thus corrected bythe birefringence of the liquid crystals.

[0070] Further, since the rotation angle of the twisted liquid crystalmolecules is large, the liquid crystal layer may be formed with a largethickness. The inexpensive driving IC may be used to maintain themaximum transmittance ratio because of the lower driving voltage. Also,the light through the liquid crystal layer remains in the linearlypolarized state without using the polarizer so that the production costis reduced for color shift correction. Moreover, a liquid crystaldisplay device having a high reliability may be fabricated with theconventional twisted nematice liquid crystal in the present invention.

[0071] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the liquid crystal displaydevice of the present invention without departing from the spirit orscope of the invention. Thus, it is intended that the present inventioncover the modifications and variations of this invention provided theycome within the scope of the appended claims and their equivalents.

What is claimed is:
 1. A liquid crystal display device, comprising:first and second substrates; a plurality of gate bus lines and data buslines on the first substrate, the gate bus lines being perpendicular tothe data bus lines; a plurality of pixels defined by the gate bus linesand the data bus lines, the pixels having a plularity of regions; atleast a pair of electrodes in each region having a common direction; anda plurality of liquid crystal molecules between the substrates.
 2. Thedevice according to claim 1 , wherein the electrodes include a dataelectrode and a common electrode.
 3. The device according to claim 1 ,wherein an electric field having an intensity changing gradually fromthe first substrate to the second substrate is applied to the liquidcrystal molecules.
 4. The device according to claim 3 , wherein theliquid crystal molecules are rotated gradually from the first substrateto the second substrate when the electric field is applied to theelectrodes.
 5. A liquid crystal display device, comprising: first andsecond substrates; a plurality of gate bus lines and data bus lines onthe first substrate in a matrix form; a plurality of pixels defined bythe gate bus lines and the data bus lines, the pixels having first andsecond regions; at least one common bus line at each pixel, the commonbus line being parallel to the gate bus line; at least a pair of firstand second electrodes in the first and second regions, respectively, thefirst and second electrodes having first and second electrode elongationdirections (θ_(EL1) and θ_(EL2)) with respect to a longitudinaldirection of the common bus line; a color filter layer over the secondsubstrate; first and second alignment layers over the first and secondsubstrates, the first and second alignment layers having first andsecond alignment directions (θ_(R1) and θ_(R2)), respectively; a liquidcrystal layer between the first substrate and the second substrate; apolarizer and a analyzer attached to the first substrate and the secondsubstrate, respectively.
 6. The device according to claim 5 , whereinthe electrodes are separated by a distance smaller than a thickness ofthe liquid crystal layer.
 7. The device according to claim 5 , whereinthe liquid crystal layer has a retardation value (Δnd) of λ/2<Δnd<λ(where Δn is an anisotropy of a refractive index, d is a thickness ofthe liquid crystal layer, and λ is a wavelength of an incident light).8. The device according to claim 7 , wherein the retardation value isapproximately 0.74λ.
 9. The device according to claim 5 , wherein thefirst alignment layer has an anchoring energy lower than that of thesecond alignment layer.
 10. The device according to claim 9 , whereinthe second alignment layer includes a polygamic acid base material. 11.The device according to claim 5 , wherein the first and second alignmentlayers have rubbing directions parallel to a polarized direction of theanalyzer.
 12. The device accordance to claim 11 , wherein the polarizerhas a polarized direction perpendicular to the polarized direction ofthe analyzer.
 13. The device according to claim 5 , wherein the firstelectrode elongation direction has an absolute value the same as that ofthe second electrode elongation direction.
 14. The device according toclaim 5 , wherein the first and second electrode elongation directionsare between 0° and 90° and between −90° and 0°, respectively.
 15. Thedevice according to claim 14 , wherein the first and second electrodeelongation directions are 90° and 90° with respect to a longitudinaldirection of the gate bus lines, respectively.
 16. The device accordingto claim 5 , wherein the first and second electrode elongationdirections are 90° and between 90° and 180°, respectively.
 17. Thedevice according to claim 16 , wherein the θ_(EL1)<θ_(R1)<θ_(EL2) andthe θ_(R2)=180°−θ_(EL1).
 18. The device according to claim 5 , whereinthe first and second electrode elongation directions have complementaryangles with respect to the longitudinal direction of the common busline.
 19. The device according to claim 18 , wherein the first andsecond alignment directions have ranges of 0°<θ_(R1)<90° and−90°<θ_(R2)<0° with respect to the common bus line, respectively. 20.The device in accordance with claim 19 , wherein the first and secondalignment directions have a relationship of θ_(R1)=−θ_(R2).
 21. Thedevice according to claim 5 , further comprising a first opticalcompensator between the polarizer and the first substrate.
 22. Thedevice according to claim 5 , further comprising a second opticalcompensator between the second substrate and the analyzer.
 23. A liquidcrystal display device having a plurality of pixels each including aplurality of regions, the device comprising: first and secondsubstrates; a liquid crystal molecular layer having liquid crystalmolecules between the first and second substrates; a plurality ofelectrodes in each region of the pixels, an electric field parallel tothe substrates being applied to the electrodes; and first and secondalignment layers over the first and second substrates, respectively, thefirst and second alignment layers having first and second alignmentdirections of θ1 and θ2 relative to an electrode elongating direction.24. The device according to claim 23 , wherein the liquid crystalmolecules in each region and a neighboring region are rotated indirections opposite with each other when an electric field is applied inthe device.
 25. The device according to claim 23 , wherein theelectrodes include at least a pair of electrodes.
 26. The deviceaccording to claim 25 , wherein the pair of electrodes include a dataelectrode and a common electrode.
 27. The device according to claim 25 ,wherein a gap between the pair of electrodes is smaller than a thicknessof the liquid crystal molecular layer.
 28. The device according to claim23 , wherein the first alignment direction is 0°<θ₁<90°.
 29. The deviceaccording to claim 23 , wherein the second alignment direction is−90°<θ₂<0°.
 30. The device according to claim 23 , wherein the first andsecond alignment directions have a relationship of θ₁=−θ₂.
 31. Thedevice according to claim 23 , wherein the liquid crystal layer has aretardation value Δnd of λ/2 (Δnd≦λ (where Δn is an anisotropy of arefractive index, d is thickness of the liquid crystal molecular layer,and λ is a wavelength of an incident light).
 32. The device according toclaim 31 , wherein the retardation value is about 0.74λ.
 33. A liquidcrystal display device having a plurality of pixels each including aplurality of regions, the device comprising: first and secondsubstrates; a liquid crystal molecular layer having liquid crystalmolecules between the first and second substrates; a plurality ofelectrodes on the first substrate in each region of the pixels, anelectric field parallel to the substrates being applied to theelectrodes, which is different from the electric field of a neighboringregion to rotate the liquid crystal molecules in opposite directions ineach neighboring region applying to the electrodes in each region; andfirst and second alignment layers over the first and second substrates,the first and second alignment layers providing for first and secondalignment directions of θ₁ and θ₂ with respect to a longitudinaldirection of a common bus line.
 34. The device according to claim 33 ,wherein the electrodes includes at least a pair of electrodes.
 35. Thedevice according to claim 34 , wherein the pair of electrodes includes adata electrode and a common electrode.
 36. The device according to claim34 , wherein the pair of electrodes have a space therebetween smallerthan a thickness of the liquid crystal molecular layer.
 37. The deviceaccording to claim 33 , wherein the first alignment direction has anangle of 0°<θ₁<90°.
 38. The device according to claim 33 , wherein thesecond alignment direction has an angle of −90°<θ₂<0°.
 39. The deviceaccording to claim 33 , wherein an angle between the first alignmentdirection and the second alignment direction is a supplementary angle.40. The device according to claim 33 , wherein the liquid crystalmolecular layer has a retardation value (Δnd) of λ/2 (Δnd≦λ (where Δn isan anisotropy of a refractive index, d is a thickness of the liquidcrystal layer, and λ is a wavelength of an incident light).
 41. Thedevice according to claim 39 , wherein the retardation value 0.74λ.